No I don't think they see gun owners as an enemy. And again, even if they did, they aren't going to do some lame one-day entrapment scenario like this to get maybe 100 people? It would be blatantly entrapment and no jury would convict any of them. As I said, if they wanted to get "the enemy", they would have said we're coming after everyone who bought an AR after 1998. Its a far bigger harvest.
I think it was a realization that they sprung this on the shops at the last second and decided to give them a day to clear their stock. That or just simple incompetence/failure to proofread.